Today, 47,000 New Yorkers and athletes from around the world will dash to the finish line today during New York City Marathon, the world’s most packed 26.2-mile race. New York Road Runners CEO Mary Wittenberg — herself a longtime runner who’s done four marathons around the country — has overseen the past six runs. “The thing about marathon day is that it’s always a good nervousness,” she says. “You have to be charged up, because you do it once a year.” This is her New York Marathon.

1. Start line — Verrazano Narrows Bridge

“The 2001 marathon was just weeks after 9/11 when the nation was still in trauma. It was such an incredible feeling seeing everyone standing on the Verrazano Narrows Bridge at the start line. Rudy Giuliani was there with race directors from around the world. They unfurled a “United We Run” banner across the bridge, the idea for which our friends in Berlin had come up with. We were also hosting the USA championship for the first time in many years, and I was looking at all the young Americans. To see them stepping up to the start line, with the national anthem playing, was extremely moving. It was a moment marked with remembrance and, at the same time, a moment that showed people running and moving again.”

“Arguably the greatest runner, world record breaker and Beijing Olympic gold medal winner Sammy Wanjiru was this incredibly outgoing personality. In 2009, he joined us in a car at the head of the marathon. Usually, guests face backward to watch the race, but he chose to watch the crowds. It’s an especially poignant memory now since Sammy’s tragic death in Kenya in May at the age of 24 [Wanjiru fell from a balcony after a dispute.] You should have seen him that day — he was like the mayor of the city.”

3. Long Island City, after the Pulaski Bridge (Miles 13-15)

“My most memorable moment in Long Island City was in 2008. We caught up with Matt Long, a NYC firefighter who was crushed by a bus in 2005. He was adamant about runnning, although he was limited with a severe limp. He had been a major athlete, and even though he was hobbling his way through the course over seven hours, he was giving big high-fives. It was one of the most inspiring moments. He was pushing his body through a lot of physical pain and yet his spirit was stronger than ever.”

4. First Avenue and Queensboro Bridge (Mile 16)

“As you come off the bridge, it’s silent and there’s this most unbelievable view. And then you hear the roar of the crowd and the music. Every year, the guys go crazy, and the crowds are cheering, and [the runners] sense it’s just 10 miles to home. They kick it up. Hendrick Ramaala once took off like he was in the middle of a running sprint and ran a 4:21 mile, one of the fastest in history. He just took off like a rocket. The crowd was going crazy.”

5. The Bronx, after the Willis Avenue Bridge (Mile 20)

“During my first year [organizing the marathon] in 1998, my job was to go along the course and make sure everything was OK. At mile 20, the hour digit on the clock wasn’t working. I took out my lipstick and made a red 1, 2, 3 and 4 every 60 minutes. I had to make sure the pros could read the clock.”

6. Finish line — Central Park

“There are so many memories here. The best finish was in 2005 — Paul Tergat and Hendrick Ramaala were racing stride for stride. They were separated by three-tenths of a second. You could see their jaws clenched. I was standing in front of them and it was not clear who would win. When Tergat won Ramaala just went flying into the ground.”